Allogenic bone marrow transplantation has been used to treat patients with storage diseases for the last decade. In the future, autologous BMT with genetically modified hematopoietic stem cells will also be used to treat these diseases. Controversy, however, still exists as to the effects of BMT on the central nervous system function of patients transplanted for storage disease. This study is to determine the effects of BMT on CNS function. The hypothesis is that allogeneic BMT will modify the natural history of CNS storage diseases.